Balanced Audio Technology REX II User manual

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REX II
WARRANTY REGISTRATION FORM
Unit Serial Number:
_______________________________________
Customer Name:
_______________________________________
Address:
_______________________________________
_______________________________________
Date of Purchase:
_______________________________________
Purchased From:
Dealer Name:
_______________________________________
Address:
_______________________________________
_______________________________________
IMPORTANT NOTE:
In order to receive the full five year product warranty, please mail
this completed form together with a copy of your sales receipt to

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Balanced Audio Technology at the address below, within thirty days
of purchase.
Failure to do so will result in the product being warrantied for one
year from the date of manufacture.
1300 First Stat Blvd. Suite A Wilmington DE 19804 Tel: [phone] Fax: [phone]

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REX II
Vacuum Tube
Balanced Stereo Preamplifier
Owner's Manual
1300 First Stat Blvd. Suite A Wilmington DE 19804 Tel: [phone] Fax: [phone]

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TABLE OF CONTENT
CURRENT SOURCES 4
CHANGING CURRENT SOURCES 5
AC SHUNT VOLTAGE REGULATORS 6
INTRODUCTION 7
Package Content 7
Physical Placement 8
Configuring the REX II 8
Connecting to your system 9
FRONT PANEL CONTROLS 10
REX II Power On sequence 10
Turning the REX II Off 108
PHASE Button and LED 11
MONO button and LED 11
MUTE button and LED 11
INPUT selection 11
VOLUME knob 11
DISPLAY format 12
FUCTION button 12
DISPLAY Brightness function 13
MUTE function 13
REX II PROGRAMMABLE FUNCTIONS 14
Parameter Definitions 15
PROGRAMMING THE REX II 15
BALANCE adjustment 15
VOLUME offsets 16
PHASE 17
MONO/STEREO 17
MAXIMUM gain 17
FIXED gain 18
DISPLAY MODE 18
INPUT NAME 19
REMOTE CONTROL FUNCTIONS 20
Volume Up/Down 20
Mute 20
Fade 20
Input 20
Display/Power 21
Fuse Protection 21
Servicing 21
Cleaning 21
RESETTING THE REX II 22
WARRANTY 23
Vacuum Tube Current Sources in REX II
Your REX II incorporates a unique feature that allows you to optimize its sound to tailor it to your
individual taste or system requirements.
The Vacuum Tube current sources incorporated in the REX II, being part of the signal gain stage, have a
direct effect on the unit’s sound. Changing the tube type used in that circuit allows the user an extra
degree of control over the sound of the unit.

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In its standard configuration the REX II current sources use the Russian 6C19 tubes. That tube is
basically a miniature version of the famous 6C33 tube, and provides, in our view, the best combination
of sonic characteristics and electrical performance.
However, the unique design of the REX II allows you to also use other tube types in that application.
Currently, the user has the following three choices for vacuum tube Current Sources:
1. The standard 6C19 tube current source as installed from the factory.
2. The 6H30 SuperTube current source which requires the purchase of the X-PAK accessory.
3. The 5881 tube current source.
NOTE: There are TWO Current Sources in REX II, located in the Power Module.
The REX II X-PAK accessory includes two current source boards.
In order to change the tube type the user needs to remove the installed Current Source boards, and replace
them with either another type, designed for a particular tube type, or install the 5881 tubes as a direct plug-in.
Only the 5881 tubes can be used directly upon the removal of the 6C19 current source board.

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Please consult the factory regarding options for other tube types that may be available in the future.
WARNING:
The following procedure should only be performed by qualified personnel
To change the current source:
1. Turn the unit OFF and wait at least 5 minutes to allow the tubes to cool down and the power
supply charge to dissipate. Remove the Power Module top cover.
2. Remove the six screws holding each current source board.
3. Pull the current source boards straight up to disengage its connectors.
4. Install the new current source boards making sure their connectors are properly aligned. Boards
will be positioned properly when the mounting holes in the circuit boards align with the standoffs.
5. Install the six mounting screws.
6. Turn the unit ON.
AC SHUNT VOLTAGE REGULATORS
The REX II preamplifier incorporates another feature that allows the user to optimize its sound – the
AC Shunt voltage regulators.
The AC Shunt voltage regulators perform the final “cleaning” of the REX II power supply rails.
They work to reduce the minute fluctuations in the DC voltages that may degrade the sound.
The AC Shunt Voltage Regulators are located in the REX II Power Module.

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They incorporate two types of vacuum tubes, user selectable for the desired sound: 6C45 and 6H30.
To change the AC Shunt tube type remove the Power Module top cover and move the board-mounted
switch S1 to desired position. The switch is located close to the center of the board.
Only the selected tubes will have their filaments running at any time.
INTRODUCTION
Thank you for your purchase of the Balanced Audio Technology REX II
preamplifier. Please read this owner's manual to obtain the full benefit of the REX II
in your system. It will provide you with the needed safety information and
operating procedures for this exceptional unit.

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WARNINGS:
To prevent the possibility of serious injury, electrical shock or fire:
DO NOT operate with the cover removed.
DO NOT expose to rain or moisture.
DO NOT defeat the ground power-plug.
DO NOT replace fuse with anything other than the same type and rating as supplied
by the factory.
Package Contents
Included in the box set should be the following:
Description Quantity
REX II Control Module 1
REX II Power Module 1
Power Cord 2
Spare Fuse 2
Torx Wrench (T-15) 1
Spare Top Cover Screws 1 10
User’s Manual 1
VK-R3 Remote Control (If ordered)
Save all the packaging material in a safe dry area for the unlikely event that
you need to return the REX II to the factory for service.
PHYSICAL PLACEMENT
It is recommended that you provide at least 6" of free space around each module
comprising the REX II preamlifier for proper ventilation.
Mount the modules on a hard surface with proper ventilation underneath.
Do not stack the REX II preamplifier on top of other units, nor vice versa.
WARNING

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Stacking the modules (putting the Control Module on top of
the Power Module) is NOT permitted.
CONFIGURING THE REX II PREAMPLIFIER SYSTEM
The REX II preamplifier system consists of two modules.
Control Module performs all the control functions associated with the
duties of the preamplifier in your system. It also receives and processes the
remote control commands.
Power Module works in conjunction with the Control Module as an outboard
power supply.
The two modules are connected by two detachable cables. In addition each module
has its own power cord that must be plugged into the power outlet.
WARNING
Make sure your REX II is powered DOWN before making or
changing ANY connections between its two modules, to the
source components or power amplifiers.
Connect the two detachable cables between the modules, making sure the channels
are connected properly.
Plug the two power cords into power receptacles.
Make all the signal connections.
CONNECTING THE REX II TO YOUR SYSTEM
Balanced Components
Use balanced XLR interconnects. All input and output connectors are clearly
marked on the back panel.
Note: The REX II XLR connectors are wired as follows:

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Pin 1: common/shield
Pin 2: positive
Pin 3: negative
For the REX II, use the Main 1 XLR Output for connection to your balanced power
amplifier. The Output 2 is configured as an RCA connector output.
Single-Ended Components
Single-ended components have RCA connectors. The REX II preamplifier is
designed to work with balanced interconnects only. If single ended components
need to be connected to the preamplifer, then the RCA/XLR adapters should be
used. These adapters are available from an authorized Balanced Audio Technology
dealer at a nominal charge.
Two types of adapters are available:
Input Adapters: RCA Female to XLR Male
Output Adapters: RCA Female to XLR Female.
REX II FRONT PANEL CONTROLS
STANDBY Button and LED
The Standby button is used to turn the unit ON and OFF and to switch the
preamplifier into its Standby mode. The LED indicates the status of the unit’s
power circuitry and has four state:
LED OFF Display OFF Unit is in OFF state
Display ON Unit is in ON state